: Obesity and related health disparities represent some of the most significant public health challenges facing society. In particular, obese Latino adolescents are disproportionately impacted by insulin resistance and type 2 diabetes. Prediabetes is an intermediate stage in the pathogenesis of type 2 diabetes and represents a critical opportunity for intervention. The Diabetes Prevention Program established that lifestyle intervention can prevent or delay type 2 diabetes in adults with prediabetes. To date, no diabetes prevention studies have been conducted in obese Latino youth with prediabetes, a highly vulnerable and underserved group. Therefore, we propose a randomized-controlled trial to test the short-term (6-month) and long-term (12- month) efficacy of a culturally-grounded, lifestyle intervention, as compared to usual care, for improving glucose tolerance and reducing diabetes risk in 120 obese Latino adolescents with prediabetes. We will further test intervention effects on quality of life, explore the potential mediating effects of changes in total, regional, and organ fat on improving glucose tolerance and increasing insulin sensitivity, and estimate the initial incremental cost-effectiveness of the intervention as compared with usual care for improving glucose tolerance. The overall approach is framed within a multilevel Ecodevelopmental model that leverages community, family, peer, and individual factors during the critical transition period of adolescence when changes in health behaviors and health outcomes are linked to future health trajectories. The intervention is guided by Social Cognitive Theory and employs key behavioral modification strategies to enhance self-efficacy and foster social support for making and sustaining healthy behavior changes. The proposal builds upon extant collaborations of a transdisciplinary team of investigators working in concert with local community agencies to address critical gaps in how diabetes prevention interventions for obese Latino youth are developed, implemented and evaluated. This innovative approach is an essential step in the development of scalable, cost-effective, solution-oriented programs to prevent type 2 diabetes in this and other populations of high-risk youth.